The concept of large kilowatt thermoelectric power generation is economically desirable since it utilizes waste heat and converts it into useful electrical power. Large amounts of low grade thermal energy may be economically converted into electric power through the use of solid state semiconductor devices. Thermoelectric energy conversion is based on the Seebeck effect which occurs in the semiconductor material subjected to a thermal gradient. Electrons in the material move in the direction of the heat flow and create a voltage potential between the hot and cold ends of the material. If the hot and cold ends are connected to complete an electrical circuit the power produced may be utilized in industrial applications. This thermoelectric phenomenon is most commonly found in thermocouples which are used, e.g., in automatic thermostats for cooking ovens, for automobile engine coolant temperature indicators or for solenoid pilot valve operated gas furnaces.
The basic advantage of the thermoelectric generator contemplated by this invention is a direct consequence of its solid state construction. The electric energy is created without rotary or moving machinery and thus the power may be produced over an extended period of time and at an extremely reduced cost due to limited wear and maintenance. By utilizing a modular configuration, generators having various power output ranges may be assembled utilizing similar elements. By employing mass production techniques for the modular structures the generation of thermoelectric energy becomes economically feasible.
An additional advantage of thermoelectric power generation relates to the use of cooling water as a heat sink. Many potential industrial users of thermoelectric power generators often require large amounts of hot water for boiler feed. Water cooled thermoelectric generator systems can decrease the energy required to supply this process hot water by performing as a feed water preheater.
Another advantage of thermoelectric generators is the extraction of waste heat from a process stream and, thereby, exposing the equipment downstream of the generator to lower operational gas temperatures. This reduction in the operation temperature of this equipment increases its useful life and reduces its life cycle costs.